Astrophotography with a 90GT and D7100

These are the first night-time shots with the D7100. They are looking pretty good! The pictures shown here are cropped from the full frame, but not altered or re-sized.

The Moon

7/27/2017 21:11CDT, D7100+90GT, 1/50s, ISO640

I got back to experimenting with the camera on the telescope. Object tracking is much improved now that I have precisely leveled the tripod with a round spirit level before adding the tracking mount. Here I’ve put the Nikon D7100 on a T-ring in line with, and at the end of, the Celestron 90GT telescope without an eyepiece. I’m getting a 2000 pixel moon image, and that’s good enough for stills in 4K video. Focusing is much easier at night, but it’s still difficult. I plugged an HDMI cable into the camera and hooked it to a computer monitor. The big screen helps my old eyes, but it’s still the same number of pixels being displayed as on the back of the camera. The exposure is not the same when the photo taken vs. setting up the shot. During set up, the camera seems to use a lower shutter speed causing the image to be blown out with highs and it that makes it hard to focus. The shot taken on release comes out much clearer due to the higher shutter speed. If I can get manual control of the set up shutter speed, I can focus better. Camera shake due to wind is still a problem. I’ve added a sandbag suspended under the tripod legs to weigh the telescope tripod down. The bag swings slightly in the breeze but at least it’s not so much of the high frequency shake I was getting before. I might be able to dampen that some by making the bag just touch the ground

I might want a higher ISO to get more depth for the corona during totality, but this seems best for this shot.

Jupiter

7/27/2017 21:24CDT, D7100+90GT, 1/125s, ISO1000

I tried Jupiter using the same setup as the moon shot. We could see two or three of Jupiter’s moons when we used the eyepiece, but I don’t see them here. I used a higher ISO and shutter speed to help freeze the shaking image.

Saturn

7/27/2017 21:28CDT, D7100+90GT, 1/60s, ISO640

The wind died down some, so I could go slower for more color.

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